Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full behavioral burden. It discloses that results are free, limited to the next 3 Japanese holidays, and include a business-day flag for today, but it omits timezone assumptions, holiday definition details, and return ordering.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single compact sentence with the key scope and return information front-loaded. 'FREE.' is slightly promotional, but the overall definition is efficient and waste-free.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter, no-output-schema utility, the description gives enough to understand the return values: next 3 Japanese public holidays and a today-is-business-day boolean. The main unresolved gap is timezone/locale context for 'today' and holiday calculations.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, so there is nothing for the description to clarify about parameter semantics. The empty schema is self-evident and the description does not need to compensate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific resource and scope: the next 3 Japanese public holidays plus whether today is a business day. It is clear what the tool returns, but it does not explicitly differentiate itself from siblings like business_days or year_planner.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The only usage-adjacent signal is 'FREE'; there is no guidance on when to use this tool versus business_days, due_date, or year_planner. The agent must infer appropriate use from the tool purpose alone.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.